António Horta-Osório, the new chief executive of Lloyds Banking Group, has announced a boardroom shakeup barely a week after taking the helm of the bailed out bank.

Lloyds announced on Wednesday morning that Helen Weir, head of the retail division, is to leave along with Archie Kane, who runs the insurance arm. The changes come as Horta-Osório changes the structure of the bank that risks being broken up by the independent commission on banking later this year.

Since joining from Santander, Horta-Osório has begun a strategic review and has concluded the products sold under the Halifax brand should be managed separately to those sold by Bank of Scotland and Lloyds TSB. He is due to report the outcome of the review in June.

While the City had been expecting boardroom changes, the speed of the departures is a surprise. Lloyds said that Kane was retiring, while Weir had decided to depart following Horta-Osório's shakeup.

Weir is thought to have been offered another boardroom role. For 2009 she had a £1m bonus, taking home £1.7m. Kane, who has spent 25 years at the company, received £1.5m, including a £885,000 bonus.

Lloyds said that Weir and Kane would receive their usual contractual entitlements on leaving the group, but no further compensation.

The bank, which is more than 40%-owned by the taxpayer, was created when Labour overrode competition concerns at the height of the 2008 banking crisis to allow Lloyds to rescue HBOS – which united Halifax and Bank of Scotland.

Restructuring

Under Horta-Osório's new structure, Lloyd's retail products and marketing division will be led by Antonio Lorenzo, group director; Lloyds TSB and Bank of Scotland Community Banks will continue to be led by Joy Griffiths, while David Nicholson will still run the Halifax Community Bank.

"These changes to the Group's management team will enable us to focus on meeting our 2011 targets, whilst putting in place some of the foundations which will enable us to deliver on our longer-term plans following the conclusion of the Strategic Review which is currently underway," said Horta-Osório.

The decision by Horta-Osório to ensure that Halifax is competing more aggressively with Lloyds may be seen by some as an effort to persuade the banking commission that there is no need to break the bank up. The commission's interim report is to be published on 11 April before a final report in September which will be scrutinised by a cabinet committee chaired by the chancellor, George Osborne.

Last week Horta-Osório announced – on his first day in the job – that he would speed up the sale of £3bn of assets, including the 600 branches that must be sold to appease EU regulations on state aid.